The present invention is directed to a louvered screen for controlling light. The screen is particularly useful in 1) making illuminated outdoor signs more readable and also has utility in 2) screening sunlight out of compartments and, 3) direct and indirect lighting applications.
Illuminated signs and signals have numerous outdoor applications from traffic control to advertising. In direct sunlight, these signs are often misinterpreted: at times the sunlight washes out the sign preventing it from being read, at other times, it will make a sign that is not illuminated appear to be on, e.g., an xe2x80x9copenxe2x80x9d or xe2x80x9cclosedxe2x80x9d sign for a bank drive-thru window. Various grates, typically metal, have been devised to try to address this problem with limited levels of success. These grates are also subject to having the vanes bent as a result of impact which can obscure the sign. In addition, the vertical vanes of the metal grates also cover the sign and are not aesthetically pleasing.
Other problems that the present invention can address include the provision of a sunscreen for compartments such as toll booths, for example. The louvered screen of the present invention can deflect the sun""s rays while permitting the booth attendant to see out. In another application, the louvered screen of the present invention can be used to soften and/or direct the light emanating from direct or indirect lighting elements.
The present invention provides a louvered screen in which a base plate of transparent plastic has embedded therein a first end of each of a series of equally, spaced, identical height louvers which extend outwardly from the base plate at an angle xcex2 other than 90xc2x0. The size of the angle xcex2 and the length of the louver, will be application driven, i.e., the desired angle and the distance the louver projects from the base, will depend on how the screen is to be used. The angle xcex2, for sunlight blocking applications, will depend on and typically be equal to the viewing angle. The length of the louver is designed, in conjunction with said angle xcex2, to optimize light flowing in a direction from said inner surface toward said outer surface while minimizing an amount of light flowing from said outer surface to said inner surface. While this is true for all applications, it is more important for some than for others (e.g., the sign over the lighting application). For applications involving sunlight screening, the angle xcex2 will be in the range between 20xc2x0 and 50xc2x0. Most preferably, the angle xcex2 is 31xc2x0 for sign screening applications involving overhead signs. For direct and indirect lighting applications, the angle xcex2 may vary between 10xc2x0 and 80xc2x0 depending on the desired lighting effect.
For applications where sunlight is involved, there is an angle xcex1 at which the sun is low enough in the sky that it has adequate abatement from the atmosphere and ceases to be a factor. Accordingly, the angle xcex1 is built into the louvered screen comprising the angle measured from a point tangent to the base of a first slat to a point tangent to the outer end of the preceding slat. For other applications, the angle xcex1 is the angle at which direct viewing of the light source is obscured. Adjacent ends of louvered screen panels are configured to enable them to be easily snapped together (e.g., by a dovetail and groove, for example) to permit coverage of a larger area.